Photoresist composition

ABSTRACT

When a low molecular weight dihydric or trihydric alcohol is added to a photoresist composition comprising a water-soluble polymer substance and a diazide photo-crosslinking agent, the fluidity of the composition is improved and the drying speed is moderately retarded and it enables the formation of a photoresist layer having a uniform film thickness and uniform drying degree. The said alcohol is exemplified by ethylene glycol, glycerol, etc. and is preferably added in an amount of 5-300 parts by weight per 100 parts by weight of the water-soluble polymer substance.

This is a division of application Ser. No. 970,363, filed Dec. 28, 1978,now U.S. Pat. No. 4,254,197, which was a continuation application ofapplication Ser. No. 496,854 filed Aug. 12, 1974, now abandoned.

The present invention relates to a photoresist composition. Moreparticularly, the invention pertains to a photoresist composition whichcan prevent coating unevenness or drying unevenness in the formation ofa photoresist layer.

Photoresists comprising a water-soluble polymer substance and a bisazidephoto-crosslinking agent have heretofore been used widely inphotographic printing or photo-etching. It is necessary for this objectto form a photoresist layer on the surface of an appointed base plate ora member to be etched. It is generally carried out by rotational coatingmethod. The photoresist layer has characteristics that it directly formsan image and its sensitivity remarkably varies according to a differencein film thickness and drying degree after coating. Therefore, saidphotoresist layer should have a uniform film thickness and be drieduniformly to obtain an even image of a high precision.

In the prior art formation of a photoresist layer, r.p.m. in rotationalphotoresist coating method or drying temperature is fixed at anappropriate value taking into account the viscosity of photoresist orthe surface state of a material to be coated. However, the prior artphotoresist has a defect that it is difficult to determine theabove-mentioned appropriate values and a uniform coating film isdifficult to obtain particularly when the base plate has a large area ora special shape, since drying is comparatively rapidly finished and thefluidity of the photoresist is poor.

An object of the present invention is to enable the formation of aphotoresist layer having a uniform film thickness by increasing thefluidity of the photoresist coated and retarding drying moderately inview of the above-mentioned defect of the prior art method. The objectof the invention can be obtained with a photoresist compositioncontaining a low molecular weight dehydric or trihydric alcohol.

Said alcohol is added in an amount of 5-300 parts by weight, andpreferably 20-200 parts by weight, per 100 parts by weight of awater-soluble polymer substance. If the amount of the alcohol added isless than the above-mentioned values, the desired effect cannot beobtained. Also, if the amount added is more than the above-mentionedvalues, sensitivity or resolving power is reduced.

The water-soluble polymer substances which may be used in the presentinvention include gelatine, homopolymers such as polyacrylamide,polyvinyl pyrrolidone, polyvinyl methyl ether and polyvinyl acetal, andcopolymers such as acrylamide-diacetone acrylamide copolymer,acrylamide-vinyl methyl ether copolymer, maleic acid-vinyl methyl ethercopolymer and acrylamidevinylpyrrolidone copolymer. Also, the bisazidephotocrosslinking agent is exemplified by4,4'-diazidostilbene-2,2'-disulfonic acid,4,4'-diazidostilbene-α-carboxylic acid and metal salts thereof.

As the low molecular weight dihydric or trihydric alcohol used in thepresent invention, there are used alcohols which are water-soluble,compatible with the water-soluble polymer substances and in the form ofa liquid at ordinary temperature and which are difficult to evaporateowing to their boiling point higher than that of water, as theirmolecular weight, melting point and boiling point are shown in the tablebelow. As such an alcohol, ethylene glycol, diethylene glycol, propyleneglycol, dipropylene glycol, 1,3-butylene glycol, 1,5-pentanediol,glycerol, etc. are effective. If the molecular weight of these alcoholsis too high, the fluidity of the photoresist becomes poor and coatingfilm-uniformizing effect is reduced. Therefore, the alcohols preferablyhave a molecular weight of 60-110.

    ______________________________________                                                                Melting  Boiling                                                  Molecular   point    point                                        Alcohol     weight      (°C.)                                                                           (°C.)                                 ______________________________________                                        Ethylene glycol                                                                           62.07       -12.6    197.7-197.8                                  Diethylene glycol                                                                         106.12      -11.5    245.0                                        Propylene glycol                                                                          76.10       Liquid   188.2                                        Dipropylene glycol                                                                        134.18      Liquid   229.2                                        1,3-Butylene glycol                                                                       90.12       Liquid   192                                          1,5-Pentanediol                                                                           104.15      -18      239-240                                      Glycerol    92.10       18       290                                          ______________________________________                                    

Also, vinyltris(β-methoxyethoxy)silane,N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane,N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, etc. are often added tothe photoresist as an adhesiveness improver, but it does not matter forobtaining the effect desired in the present invention.

The photoresists according to the present invention containing theabove-mentioned dihydric or trihydric lower molecular weight alcoholsbecome a solution of a high boiling point which is difficult toevaporate and their fluidity is increased by reduction in theirviscosity. On coating of the photoresists, therefore, a uniform coatingfilm can be easily obtained irrespective of the shape of a base plate tobe coated or the coating area and the influence of r.p.m. in rotationalcoating method is reduced. Further, on drying of the photoresists,drying is retarded and thereby it is possible to prevent dryingunevenness caused by a change in drying temperature or heatingunevenness and form a photoresist layer having a uniform film thickness.

The following examples, in which all parts are expressed by weight,unless otherwise indicated, will serve to illustrate the practice of theinvention in more detail.

EXAMPLE 1

Two photoresist liquids were prepared by dissolving one part ofpolyacrylamide as a water-soluble polymer substance and 0.2 part ofsodium 4,4'-diazidostilbene-2,2'-disulfonate as a bisazide crosslinkingagent in 100 parts of water and then adding or not adding 0.2 part ofethylene glycol to the solution. Each photoresist liquid was droppedonto a 200 mm×150 mm glass base plate, rotation-coated at 150 r.p.m. anddried by a 100 W infrared heater for 5 minutes to form a photoresistlayer. An optical mask, in which round holes of 0.4 mm in diameter weretwo-dimentionally arranged at a pitch of 0.65 mm, was placed at adistance of about 1 cm from the photoresist layer. Exposure was carriedout with a point source of light and development was then carried out bya water spray (water pressure 1 kg/cm²). When the respective images thusobtained were observed, it was found that the image formed with thephotoresist containing ethylene glycol produced no unevenness incontrast with the image formed with the photoresist containing noethylene glycol.

EXAMPLE 2

Two photoresists were prepared by dissolving a water-soluble polymersubstance consisting of 0.5 part of polyvinyl pyrrolidone and 0.5 partof polyacrylamide, 0.4 part of sodium4,4'-diazidostilbene-2,2'-disulfonate as a bisazide crosslinking agentand 0.05 part of N-β-(aminomethyl)-γ-aminopropyltrimethoxysilane as anadhesiveness improver in 100 parts of water and then adding or notadding 0.5 part of propylene glycol to the solution. Each photoresistwas coated onto the inner surface of the front panel of a 20-inch colortelevision receiver by a rotational coater and then dried by an infraredheater provided with ten 200 W lamps on the whole of one side for 3minutes, drying having been finished at a panel temperature of 45° C. Aultraviolet ray was irradiated through a shadow mask, in which holes of0.34 mm in diameter were two-dimentionally arranged at a pitch of 0.65mm, at an illuminance of 1500 luxes for two minutes, and development wascarried out by a water spray (water pressure 1 kg/cm²). As a result, thephotoresist containing propylene glycol produced no unevenness in imagein contrast with the photoresist containing no propylene glycol. Also,the unevenness produced in the photoresist containing no propyleneglycol was due to a difference in the size of the formed dot image. Thereason therefor is considered to be a difference in sensitivity causedby nonuniformity in the film thickness of photoresist or the dryingdegree of film.

EXAMPLE 3

Two photoresists were prepared by dissolving a mixture of 1.5 parts ofpolyvinyl pyrrolidone and 1 part of gelatine as a water-soluble polymersubstance, 0.3 part of sodium 4,4'-diazidostilbene-2,2'-disulfonate as abisazide crosslinking agent, and 0.02 part ofN-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane as an adhesivenessimprover in 100 parts of water and then adding or not adding 2 parts of1,3-butylene glycol as an alcohol. Each photoresist was subjected to thesame experiment as described in Example 2. It was found that the imageproduced with the photoresist containing the alcohol produced nounevenness.

What is claimed is:
 1. A photoresist coated article which comprises aphotosensitive photoresist layer on a glass substrate in which aphotoresist composition is coated on the substrate by rotation of saidsubstrate and the composition is allowed to dry to form said photoresistlayer, the photoresist composition comprising a bisazidephoto-crosslinking agent, a water-soluble polymeric substance capable ofbeing photo-crosslinked by said bisazide photo-crosslinking agent, and 5to 300 parts by weight per 100 parts by weight of said water-solublepolymeric substance of dihydric alcohol having a molecular weight of 60to
 110. 2. An article according to claim 1, wherein said alcohol isselected from the group consisting of ethylene glycol, diethyleneglycol, propylene glycol, 1,3-butylene glycol, and 1,5-pentanediol. 3.An article according to claim 1, wherein said water-soluble polymericsubstance is selected from the group consisting of gelatine,polyacrylamide, polyvinyl pyrrolidone, polyvinyl methyl ether, polyvinylacetal, acrylamide-diacetone acrylamide copolymers, acrylamide-vinylalcohol copolymers, acrylamide-vinylpyrrolidone copolymers and maleicacid-vinyl methyl ether copolymers.
 4. An article according to claim 1,wherein said bisazide photo-crosslinking agent is selected from thegroup consisting of 4,4'-diazidostilbene-2,2'-disulfonic acid,4,4'-diazidostilbene-α-carboxylic acid and metal salts thereof.
 5. Anarticle according to claim 1, wherein said photoresist compositionfurther contains an adhesiveness improver.
 6. An article according toclaim 5, wherein said composition further contains an adhesion promotorselected from the group consisting of vinyltris (β-methoxyethoxy)silane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, andN-β-(aminoethyl)-γ-aminopropyltrimethoxysilane.
 7. A photoresist coatedarticle which comprises a photosensitive photoresist layer on a glasssubstrate in which a photoresist composition is coated on the substrateby rotation of said substrate and the composition is allowed to dry toform said photoresist layer, the photoresist composition before dryingcomprising an aqueous solution containing water, a bisazidephoto-crosslinking agent, a water-soluble polymeric substance capable ofbeing photo-crosslinked by said bisazide photo-crosslinking agent, and 5to 300 parts by weight per 100 parts by weight of said water-solublepolymeric substance of dihydric alcohol having a molecular weight of 60to
 110. 8. An article according to claim 7, wherein said alcohol isselected from the group consisting of ethylene glycol, diethyleneglycol, propylene glycol, 1,3-butylene glycol, and 1,5-pentanediol. 9.An article according to claim 8, wherein said water-soluble polymericsubstance is selected from the group consisting of gelatine,polyacrylamide, polyvinyl pyrrolidone, polyvinyl methyl ether, polyvinylacetal, acrylamide-diacetone acrylamide copolymers, acrylamide-vinylalcohol copolymers, acrylamide-vinylpyrrolidone copolymers and maleicacid-vinyl methyl ether copolymers.
 10. An article according to claim 9,wherein said bisazide photo-crosslinking agent is selected from thegroup consisting of 4,4'-diazidostilbene-2,2'-disulfonic acid,4,4'-diazidostilbene-α-carboxylic acid and metal salts thereof.
 11. Anarticle according to claim 10, wherein said composition further containsan adhesion promotor selected from the group consisting of vinyltris(β-methoxyethoxy) silane,N-β-(aminoethyl)γ-aminopropylmethyldimethoxysilane, andN-β-(aminoethyl)-γ-aminopropyltrimethoxysilane.
 12. An article accordingto claim 7, wherein said bisazide photo-crosslinking agent, saidwater-soluble polymeric substance and said dihydric alcohol aredissolved in a solvent consisting essentially of water.
 13. An articleaccording to claim 12, wherein said solvent consists of water.